Purification of alkyl aryl hydrocarbons



di er N United States Patent PURIFICATION OF A'LKYL ARYL HYDROCARBONSJames C. Kirk, Lake Charles, La., and Edsel L. Miller, Houston, Tex.,assignors to Continental Oil Company,

Ponca City, Okla., a corporation of Delaware No Drawing. ApplicationJanuary 8, 1958 Serial No. 707,686

10 Claims. (Cl. 260-674) The present invention relates to the productionof alkyl aryl hydrocarbons which are substantially free of colorprecursors. Somewhat more particularly this invention provides a methodfor producing such alkyl aryl hydrocarbons which, upon sulfonationandneutralization, yield a substantially color-free salt.

Sulfonation of alkyl aryl hydrocarbons has generally followed theprocedure wherein about 1.3 to 2 parts by weight of 100 to 105 percentsulfuric acid or olepm is used per part by weight of the alkyl arylhydrocarbon. Other sulfonating agents have been used but whatever agentwas used, the resulting sulfonic acid when neutralized witha base suchas sodium hydroxide, yields a dark-colored sulfonate. Since dark-coloredsulfonates can be used only in relatively few applications, variousmethods have been heretofore suggested for removing such color bodieswhich impart color to the sulfonate. These methods have involvedtreating the aqueous solution of the sulfonate with bleaching agentssuch as peroxide or acidic reagent such as sulfuric or hydrochloricacid. Other methods have involved blowing the aqueous sulfonate solutionwith oxidizing gases such as free oxygen. None of these methods havebeen entirely satisfactory, generally because they have involved anundesirable expenditure of materials and time, and furthermore the finalproduct so obtainedhas not been improved greatly in color and theresulting improvement is only transitory in nature.

It is, therefore, a principal object of this invention to provide animproved process, which process obviates the disadvantages of the priorart methods. It is another object of our invention to provide a methodfor the removal of color precursors from alkyl aryl hydrocarbons wherebysubstantially colorless sulfonates can be produced by the sulfonation ofsuch alkyl aryl hydrocarbons followed by neutralization. Further objectsand advantages of the invention will become apparent from the followingdescription.

In its broadest aspects the invention comprises the alkylation of anaromatic hydrocarbon such as benzene or toluene with an olefincontaining from 8 to 18 carbon atoms in the molecule in the presence ofan alkylation catalyst under alkylation conditions. Following thealkylation reaction the resulting mixture is allowed to remain quiescentuntil 2'layers are formed, an organic layer and a catalyst sludge layer.The catalyst sludge is removed and then the alkyl aryl hydrocarbonrecovered from the organic layer by fractional distillation. The alkylaryl hydrocarbon is then treated with an oxidizing agent in the presenceof acid and water andat a temperature varying from 20 to 100 C. for aperiod of time varying from to 60 minutes. The oxidizing mixture is thenallowed to remain quiescent for a period of time until the oxidizingmaterials have settled out. The oxidizing materials are withdrawn andthe alkyl aryl hydrocarbon which is partially freed of color precursorsis treated with about l to 5 weight percent of sulfuric acid based uponthe, Weightofthe alkyl aryl hydrocarbon (2,932,677 Patented Apr. 12,1960 at a temperature varying from 25 to C. for a period of time varyingfrom 5 to 30 minutes. The resulting mixture is allowed to remainquiescent until the acid has settled out. By this procedure two layersare formed, the lower acid layer which contains oxidized colorprecursors and an upper layer'which consists of the alkyl arylhydrocarbon substantially free of color precursors.- The alkyl arylhydrocarbon is then recovered and upon subsequent sulfonation andneutralization there is obtained an alkyl aryl sulfonate which is,substantially colorless.

While We do not wish to be bound by any particular theory regarding thereactions which take place during the chemical treatment of the aromatichydrocarbon, we believe that in the preparation of alkyl arylhydrocarbons by the reaction of an alkylating agent with an aromatichydrocarbon in the presence of a Friedel-Crafts catalyst such asaluminum chloride, side reactions occur which lead to the formation ofpolynuclear aromatic hydrocarbons. These polynuclear hydrocarbons imparta blue fluorescenceto the alkyl aryl hydrocarbon and are in partresponsible for the dark color of the product obtained on sulfonationand neutralization of the alkyl aryl hydrocarbon. Analysis indicatesthat the polynuclear hydrocarbons are primarily 9-alkyl anthracenes and9,10-dialkyl anthracenes and may be present in the alkyl arylhydrocarbon in concentrations up to .125 gram per liter and .075 gramper liter respectively. 9

Before proceeding with specific examples illustrating our invention, itmay be well to indicate in general the nature and the amounts of thedifierentmaterials required in the process.

The alkyl aromatic hydrocarbons which may be freed of polycyclicaromatic compounds by the process of this invention are those alkylaromatic hydrocarbons prepared by the condensation of an aromatichydrocarbon and an alkylating agent in the presence of a Friedel-Craftcatalyst, particularly aluminum chloride. The aromatic hydrocarbon maybe benzene or a low molecular weight alkyl benzene or dialkylbenzenesuch as toluene, ethyl benzene, cumene, 0-, m-, and p-xylene, mixturesof xylenes, naphthalene, alpha-methyl naphthalene, beta-methylnaphthalene, diphenyl, the aromatics contained in petroleum fractions,and the like. The alkylating agent may be an alkyl halide, alkanol, orolefin having from about 10 to about 20 carbon atoms. Included among thealkyl halides are l-chlorodecane, lauryl chloride, 1- chloro-octadecane,and l-bromodecane. Suitable alkanols are lauryl alcohol, decanol, andstearyl alcohol. Suitable olefins are decene-l, decene-2, dodecene-l,dodecene-2, pentadecenes, octadecenes, and olefins obtained by thepolymerization of ethylene, propylene, isobutylene and their mixturessuch as tetrapropylene, pentapropylene and hexapropylene.

The oxidizing agents suitable for use in the process of this inventionare the sulfuric acid solutions of the chromates including sodium andpotassium chromate and dichromate and chromium trioxide. Ozone may alsobe used. The preferred oxidizing agents are sulfuric acid solutions ofchromium trioxide or ozone. Generally for treatment of parts of thealkyl aromatic hydrocarbon an oxidizing solution containing from 0.25 to0.75 parts of oxidizing agent, 1.5 to 5 parts of water and 2 to 6 partsof 96% sulfuric acid is efiective in removing polycyclic hydrocarbons. Alarger amount of oxidizing solution may be used but is unnecessary fortreatment of alkyl aromatic hydrocarbons prepared as described above.,

prefer to etfect the purification at 60 C. for a period of minutes. Whenozone is used as the oxidizing agent, from about 0.3 to 0.6 grams-ofozone is used per 100 parts of hydrocarbon. The. ozone is. passed intothe hydrocarbomduring a period of item about 20..to; 60 minutes.-Eollowing the oxidation treatment, the treated mixture is allowedftosettleand a dark-colored sludge withdrawnzusing, if; desired, a small.amount, ofa. filter inggaidtoqassist in. coagulating the. sludge- The.hydroca ghon isgthen agitated vigorously.with 1, to 5%, and preferably2%, by weight of concentrated sulfuric, acid at a tempifirature' ot from25 to 80. C. for from 5 to. 30 minutes. The sludge is. then removedand.the. hydro.-

' carbon treated with a basic clay such as Attapulgus clay on, a:Klett-Summerson Photo-electric Colorimeter using a4-centimete z celland'a Klett Color Filter No. 42. The is. then equal to'the readingotthesamplerdie dedby. e ad ao thestandard. Obviously, the hi he e RQ-Q.numbe th more nten th y ow lor I'Qfj thes dium alky yl ulton te l r s no r: t d scl se h x f l lllfi; f. t e p esent; invcnztion still moreclear1y,ythefollowing illustrative examples will be given. It is to beunderstood, howeventhat the examples given hereinafter are not intended;for limiting the invention but rather to illustrate the principles andpractices to be observed in producingthe improvement according to myinvention. Parts given are parts by weight.

Example 1 A vessel equipped with a high speed agitator was charged with.100 parts of pentadecylbenzene prepared by v the condensation ofpentapropylene with benzene in hep sen e of a uminum. c l r d Wh e.gitating, 5 p r s i. an. ox d in s luti n. p p d y addin 4 Parts ot' homium. r oxide o :6. pa t lo't w ter. w s. added an h agit pn ntnuedfor' 0 m nu es t.3.0." '0 Tw parts of Attapulgusclay was added to,the. agitating mixt r.e ..andjthen the; mixture was allowed, to. stand,quiescent allot; which. the hydrocarbon was decantedfrom, the darksludge, The hydrocarbonwasthen agitated for min,- utes .at=,1 .00,? C.with, 5. parts of Attapulgus clay andfilteredthrough. a Hyflomat, toyield hydrocarbon having no. fluorescent bloom.

Anaylsin-The, initial pentadecylbenzene analyzed 0. .2 2,. per. lit r o.9- a .y anthracenes and. 0- 7 p iter; o 9.,lfl ialky an hracenes- Qn.fon tion. n neutralization a sulfonate-having an R.C.D. of 2 .70'wasobtained.

The pent-adecylbenzene treated above analyzed0000 eve iterof nthr cenes.Onz ulfonation. ndne ra ization a sulfonate having an R.C .D. of 1.76was obtained. 7

Although the use. of the: clay. treatmentgivesa somewhat bettenproduct.as. far as color is. concerned, it may be desirable to eliminate the,clay treatment in; many cases; This is truebecauseof theoperatingditiiculties inyolyedwhenaclay treatment is used.

Example 2' 4 I Example 3 When treated only with clay and no oxidation orsulfuric acid treatment, the hydrocarbon gave a sulfonate having anR.C.D. of 2.70.

Example! When treated with. 3 .partstof'concentrated; sulfuric acid andthen 5 partsoficlay, the hydrocarbon gave a sulfonate havingzan R.C.D of2.68..

The. foregoing experiments demonstrate that it is neces-' sary to treatthe alkyl benzene prepared by the condensation of an alkylation agentwith benzene in the presence of aluminum chloride'with both an'oxidizingsolution and sulfuric acid in order to obtain a sulfonate havingexcellent color. Either the use of the oxidizing solution or sulfuricacid alone does not give as good a result as when both are used.

Example 5 Dodecylbenzene. prepared by the alkylation of benzene withdodccenein thepresence of aluminum chloride was treated as inthepreceding 4examples. The -sulfonates obtained had the followingcolors:

and clay 2.58

From dodecylbenzene treated. with oxidizing agent,

sulfuric acid and clay 1.l1

Example 6- Into 130' parts of pentadecylbenzene'preparedas described inExample 1,05 parts. of ozone was bubbled over a period of 3.0 minutes at25 C. The mixture was then agitated with 2parts of Attapulgus clay and adark sludge removed by decanting the hydrocarbon. The hydrocarbon wasthentreated at 60 C. for 20 minutes with 5 parts. of sulfuric acid (96%),'the.,s1udge removed by decanting, the. hydrocarbon was then contactedwith 2' parts ofjAttapulgusclay and" filtered. The product was, clear,colorlessand bright, and had an R.C;D. of 1.70.

Wehave found. thatinthose. few cases .wherethe met at salt o..the,alky1-.ary1su1fonic acid produced by the. process of this.;in vention is still slightly colored that product may be bleached.,.very easilyby methods well known toithoseskilledinnthe.art.. Such. bleaching meth:ods includethe, treatmentof the. product with a. bleaching ent. such asa peroxide. o1.v bleaching by meansv of electrolysis. We. have. foundfurther that: if. these color. precursprshave. not been; removedbytheprocessv of this invention, it is rather diflicult tobleachtheresulting product andthe resultisonly-transitory.

While particular embodiments of the. invention. have been, described, itwill .beunderstood, of course, that the invention is not, limited.thereto. since many modifications may be; made, and. it is-, ther.efore,contemplated to cover by theappended, claimsany such modificationsasfallwithinthe, true spirit and,v scope of the invention.

he invention, having; thus. been described, what is claimed and,desired, to besecured by LettersLPatent is:

1. A,meth0d;10f. removing colon precursors, of the typewhichadverselyafiectalkyl ary l; sulfonates, from anyalkylaryl-hydrocarbon mixture,produced ina Friedel- Craftspallcylation,reactionandcontaining 8. to 18carbon atoms; in. the alkyl. group-, saidmethod comprising thetreatmenkof. said mixturewith. an oxidizing agent selected fromrthegroup. consisting of-sodium chromate, potassium chromate. sodiumdichromate, potassium, dichromate, chromium trioxide, and ozonein thepresence ofwaterand sulfuricacid at a temperaturevarying from acclimate-100 C2 and for -aperiod varying from about 5 to 60 minutes, allowing theoxidized products to settle out thus forming two layers, an upper layercomprising the alkyl aryl hydrocarbon partially freed of colorprecursors and substantially freed of color precursors of the alkylanthracene type and a lower layer comprising the oxidized products,separating the two layers, contacting said recovered upper layer with 1to 5 weight percent sulfuric acid based on the weight of said alkyl arylhydrocarbon at a temperature varying from about 25 to 80 C. for a periodof time varying from about 5 to 30 minutes, allowing the mixture toseparate into a lower layer consisting predominantly of the alkyl arylhydrocarbon, and then separating the layers to recover thereby the alkylaryl hydrocarbon substantially free of color precursors.

2. The method of claim 1 wherein the oxidizing agent is a chromiumtrioxide.

3. The method of claim 2 wherein the alkyl aryl hydrocarbon mixturecomprises pentadecylbenzene.

4. The method of claim 2 wherein the alkyl aryl hydrocarbon mixturecomprises dodecylbenzene.

5. The method of claim 1 wherein the oxidizing agent is ozone.

6. The method of claim 5 wherein the alkyl aryl hydrocarbon mixturecomprises pentadecylbenzene.

7. The method of claim 1 wherein the oxidizing agent is a sodiumchromate.

8. The method of claim 1 wherein the oxidizing agent is a potassiumchromate.

9. The method of claim 1 wherein the oxidizing agent is a sodiumdichromate.

10. The method of claim 1 wherein the oxidizing agent is a potassiumdichromate.

References Cited in the file of this patent UNITED STATES PATENTS1,963,555 Morrell .a June 19, 1934 2,688,633 Cohen Sept. 7, 19542,806,875 Geiser Sept. 17, 1957 2,875,257 Thompson Feb. 24, 1959 FOREIGNPATENTS 143,193 Great Britain Feb. 3, 1921

1. A METHOD FO REMOVING COLOR PRECURSORS, OF THE TYPE WHICH ADVERSELYAFECT ALKYL ARYL SULFONATES, FROM AN ALKYL ARYL HYDROCARBON MIXTURE,PRODUCED IN A FRIEDELCRAFTS ALKYL LATION REACTION AND CONTAINING 8 TO 18CARBON ATOMS IN THE ALKYL GROUP, SAID METHOD COMPRISING THE TREATMENT OFSAID MIXTURE WITH AN OXIDIZING AGENT SELECTED FROM THE GROUP CONSISTINGOF SODIUM CHROMATE, POTASSIUM CHROMATE, SODIUM DICHROMATE, POTASSIUMDICHROMATE, CHROMIUM TRIOXIDE, AND OZONE IN THE PRESENCE OF WATER ANDSULFURIC ACID AT A TEMPERATURE VARYING FROM ABOUT 20 TO 100*C. AND FOR APERIOD VARYING FROM ABOUT 5 TO 60 MINUTES, ALLOWING THE OXIDIZEDPRODUCTS TO SETTLE OUT THUS FORMING TWO LAYERS, AN UPPER LAYERCOMPRISING THE ALKYL ARYL HYDROCARBON PARTIALLY FREED OF COLORPRECURSORS AND SUBSTANTIALLY FREED OF COLOR PRECURSORS OF THE ALKYLANTHRACENE TYPE AND A LOWER LAYER COMPRISING THE OXIDIZED PRODUCTS,SEPARATING THE TWO LAYERS, CONTACTING SAID RECOVERED UPPER LAYER WITH 1TO 5 WEIGHT PERCENT SULFURIC ACID BASED ON THE WEIGHT OF SAID ALKYL ARYLHYDROCARBON AT A TEMPERATURE VARYING FROM ABOUT 25 TO 80*C. FOR A PERIODOF TIME VARYING FROM ABOUT TO 30 MINUTES, ALLOWING THE MIXTURE TOSEPARATE INTO A LOWER LAYER CONSISTING PREDOMINANTLY OF THE ALKYL ARYLHYDROCARBON, AND THEN SEPARATING THE LAYERS TO RECOVER THEREBY THE ALKYLARYL HYDROCARBON SUBSTANTIALLY FREE OF COLOR PRECURSORS.